CFG: 'continue' statements jump to loop condition instead of increment code

[llvmbot]

Bugzilla Link	2763
Resolution	FIXED
Resolved on	Nov 07, 2018 00:22
Version	unspecified
OS	MacOS X
Attachments	Contains a single short instance method that produces a false dead store
Reporter	LLVM Bugzilla Contributor
CC	@tkremenek

Extended Description

The static analyzer finds dead stores, which it thinks are dead due to a later assignment that can't be reached because the first assignment is always followed by a branch that misses the second. I expect this is a more general problem untangling code paths, but this is a good illustration.

checker-85 (2008-08-28 14:46:11)
Mac OS X 10.5.4

Attached is a small objc method that reproduces a false dead store positive. It's derived from a larger example and probably doesn't make a great deal of sense from a semantic point of view. The gist is that the loop counter "index" is incremented by one or more on each iteration.

I can make this a standalone example if you'd prefer, or you can just drop this code into any Foundation based class implementation you have lying about.

[llvmbot]

assigned to @tkremenek

[tkremenek]

This was a low-level CFG bug. It's quite startling it wasn't discovered earlier.

Fixed:

http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20080901/007420.html

Will roll into checker-89 (building right now).

[tkremenek]

Integrated into checker-89.

[tkremenek]

Tom: Can you verify that this change removes these idiomatic false positives from your code?

[llvmbot]

Ted asked me to "verify that this change removes these idiomatic false positives", which it in fact it does (hooray!) so I'm setting the status to "Verify". Hope that's the correct step for me.

[tkremenek]

Thanks Tom!